Round cut gemstone exhibiting excellent optical brilliance

ABSTRACT

A gemstone including a substantially round girdle, a crown extending in a first direction from the girdle, and a pavilion extending in a second direction from the girdle opposite the first direction. The gemstone has 73 uniquely arranged and angled facets, 33 of which are in the crown, and 40 of which are in the pavilion. The height of the crown is preferably between 12.5 to 19.5% of the diameter of the stone, the total depth of the stone is preferably between 59-62.9% of the diameter of the stone, the depth of the pavilion is between 42.9 to 44.5% of the diameter of the stone, and the diameter of the table is preferably between 53-60% of the diameter of the stone.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Provisional Patent Application No. 62/090,617, filed Dec. 11, 2014, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to round cut gemstones exhibiting excellent optical brilliance. In particular, the present invention relates to a round-cut diamond with superior optical characteristics compared to that of industry standard round cut diamonds.

BACKGROUND OF THE INVENTION

The round cut diamond is the most popular diamond shape, representing approximately 75% of all diamonds sold. Due to the mechanics of its shape, the round diamond is generally superior to fancy diamond shapes for reflection of light, thereby maximizing potential brightness. Virtually all round diamonds are brilliant-cut, meaning they have 58 facets (or 57 facets when there is no culet present).

Round diamonds cost more on a per carat basis than fancy shapes for two reasons; the demand for round diamonds is very high, and the yield is relatively low. Because more of the rough stone is lost in the cutting of a round diamond, the cost of each carat retained is higher. As such, a typical round diamond may cost 25-35% more than a similar fancy shape.

The round diamond began to rise in popularity in 1919 with the publication of Marcel Tolkowsky's thesis “Diamond Design: A Study of the Reflection and Refraction of Light in Diamond.” Tolkowsky's work described the ideal proportions of a round cut diamond for maximizing light return (or brilliance) and dispersion (or fire). The original Tolkowsky specifications have since been modified as the cut mechanics for round diamonds have perfected over time. These theoretical advancements, as well as advancements in technology (such as the use of lasers in diamond cutting), have been adopted by diamond cutters to produce the round brilliant cuts currently being made.

One of the main characteristics of a properly cut diamond is light return or light performance, i.e., the amount of light returned to the eye from the diamond. The higher the light performance grade, the greater the brilliance (white light) and fire (colored light) of the diamond. Light performance is impacted by, among other things, the number, shape, angles and arrangement of the facets on the cut diamond. However, just increasing or decreasing the number and angle of the facets does not directly correlate to an increase in light performance. In fact, sometimes an increase in the number of facets can result in a diamond that is dull and lifeless, exactly the opposite of what is desired. Thus, arriving at the exact and precise combination of angles and facets to create the perfect formula for the highest light return is not a simple matter.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to enhance the brilliance of round cut diamonds so they exceed the brilliance and light performance of ideal cut round diamonds.

The round cut diamond of the present invention includes a substantially circular girdle; a crown extending in a first direction from the girdle; and a pavilion extending in a second direction from the girdle opposite the first direction. The round cut diamond has 73 uniquely arranged and angled facets, 33 of which are in the crown, and 40 of which are in the pavilion. The height of the crown is preferably between 12.5 to 19.5% of the diameter of the round cut diamond, the total depth of the round cut diamond is preferably between 59-62.9% of the diameter of the round cut diamond, and the depth of the pavilion is preferably between 42.9-44.5% of the diameter of the round cut diamond.

The crown has a table and eight main facets surrounding the table, eight star facets, and sixteen top-half facets around the girdle. In the preferred embodiment, the diameter of the table 5 is preferably 53-60% of the diameter of the round cut diamond, the eight main facets are cut at an angle of approximately 32-36°, the eight star facets are cut at an angle of approximately 22-26°, and the sixteen top-half facets are cut at an angle of approximately 39-44°. All of these angles are relative to a plane parallel to the surface of the table.

The 40 facets of the pavilion include eight main pavilion facets extending from the culet to the girdle of the round cut diamond, sixteen upper half facets, and sixteen lower half facets. Preferably, and relative to a plane parallel to the face of the girdle, the eight main pavilion facets are each at an angle of approximately 40.6-41.4°, the upper half facets are each at an angle of approximately 41.4-42.0°, and the lower half facets are each at an angle of approximately 42.0-42.9°.

The present invention's unique combination of angles and faceting creates exceptional fire, brilliance and scintillation. Specifically, the present invention's use and arrangement of the unique faceting and angles achieves an average 96% (“Excellent”) light performance, as per the Gem Certification & Assurance Lab (GCAL), achieves a Gemological Institute of America (GIA) grading of “Round Brilliant,” and also achieves a grading of “Very High” in each of brilliance, fire and sparkle from GemEx Systems, Inc. (GEMEX). Accordingly, unlike standard round cut diamonds, the present invention uses a unique combination of 73 facets (33 in the crown, and 40 in the pavilion) to achieve a gemstone having significantly enhanced light performance characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures are for illustration purposes only and are not necessarily drawn to scale. The invention itself, however, may best be understood by reference to the detailed description which follows when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevation view of a gemstone according to the present invention;

FIG. 2 is a top view of the gemstone shown in FIG. 1; and

FIG. 3 is a bottom view of the gemstone of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will next be illustrated with reference to the figures. Such figures are intended to be illustrative rather than limiting and are included herewith to facilitate the explanation of exemplary features of embodiments of the present invention. Unless otherwise noted, the figures are not to scale, and are not intended to serve as engineering drawings.

Referring now to the drawings, FIG. 1 is a side elevation view of a round cut diamond 1 according to the present invention. Although the following description relates to a round cut diamond, it will be readily apparent to one of skill in the art that the unique angles and faceting described herein can be applied to any precious or semi-precious gemstone.

As shown in FIG. 1, the round cut diamond 1 includes a substantially circular girdle 2; a crown 3 extending in a first direction from the girdle 2; and a pavilion 4 extending in a second direction from the girdle 2 opposite the first direction. The round cut diamond 1 has 73 uniquely arranged and angled facets, 33 of which are in the crown 3, and 40 of which are in the pavilion 4. The height CH of the crown 3 is preferably between 12.5 to 19.5% of the diameter D of the round cut diamond 1, the total depth DT of the round cut diamond 1 is preferably between 59-62.9% of the diameter D of the round cut diamond 1, and the depth PD of the pavilion 4 is preferably between 42.9-44.5% of the diameter D of the round cut diamond 1. It is also preferred that the thickness of the girdle 2 is 1% to 7% of the diameter D of the round cut diamond 1, i.e., from “thin to very thick.”

FIG. 2 is a top view showing the crown 3 of the round cut diamond 1 of FIG. 1. As shown in FIG. 2, the crown 3 has a table 5 and eight main facets 6 surrounding the table 5. Each of the eight main facets 6 are preferably equally spaced around the table, and extend from the table 5 to the girdle 2. The crown 3 also has eight star facets 7. Each of the eight star facets 7 is positioned between adjacent facets of the eight main facets 6 and the table, and define respective sides of the table 5. The crown 3 further includes sixteen top-half facets 8 around the girdle 2. The sixteen top-half facets 8 are arranged such that a respective pair of top-half facets 8 are positioned between adjacent facets of the eight main facets 6 and the girdle.

In the preferred embodiment, the diameter TD of the table 5 is preferably 53-60% of the diameter D of the round cut diamond 1, the eight main facets 6 are cut at an angle of approximately 32-36°, the eight star facets 7 are cut at an angle of approximately 22-26°, and the sixteen top-half facets 8 are cut at an angle of approximately 39-44°. All of these angles are relative to a plane parallel to the surface of the table 5.

Turning now to FIG. 3, the pavilion 4 of the round cut diamond 1 of FIG. 1 is shown. The pavilion 4 includes 40 uniquely angled and arranged facets. These 40 facets of the pavilion 4 include eight main pavilion facets 9 extending from the culet to the girdle 2 of the round cut diamond 1, and preferably equally spaced around the pavilion 4. The pavilion 4 also includes sixteen upper half facets 10. The sixteen upper half facets 10 are arranged such that a respective pair of upper half facets 10 are positioned between adjacent facets of the eight main pavilion facets 9 and the girdle 2. The pavilion 4 further includes sixteen lower half facets 11. The sixteen lower half facets 11 are arranged such that a respective pair of lower half facets 10 are positioned between adjacent facets of the sixteen upper half facets 10 and the girdle 2.

Preferably, and relative to a plane parallel to the face of the girdle 2, the eight main pavilion facets 9 are each at an angle of approximately 40.6-41.4°, the upper half facets 10 are each at an angle of approximately 41.4-42.0°, and the lower half facets 11 are each at an angle of approximately 42.0-42.9°.

Although the present invention is not limited in the style of the culet used, the culet is preferably a pointed culet (i.e., 0% of the width of the gemstone) to a substantially flat culet having an area of 3% or less of the diameter D of the round cut diamond 1.

The present invention's unique combination of angles and faceting creates exceptional fire, brilliance and scintillation. Specifically, the present invention's use and arrangement of the unique faceting and angles achieves an average 96% (“Excellent”) light performance, as per the Gem Certification & Assurance Lab (GCAL), achieves a Gemological Institute of America (GIA) grading of “Round Brilliant,” and also achieves a grading of “Very High” in each of brilliance, fire and sparkle from GemEx Systems, Inc. (GEMEX). Accordingly, unlike standard round cut diamonds, the present invention uses a unique combination of 73 facets (33 in the crown, and 40 in the pavilion) to achieve a gemstone having significantly enhanced light performance characteristics.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications will become apparent to those skilled in the art. Therefore, the present invention should not be limited by the specific disclosure herein. For example, although the present invention has been described with respect to a cut diamond, the unique angles and faceting can be equally applied to all precious or semi-precious stones to achieve enhanced brilliance and light performance. 

What is claimed is:
 1. A gemstone comprising: a substantially round girdle; a crown extending in a first direction from the girdle, the crown having a table, eight main facets surrounding the table, eight star facets positioned between adjacent facets of the eight main facets and the table, and sixteen top half facets, wherein a respective pair of the sixteen top-half facets are positioned between the adjacent facets of the eight main facets and the girdle; and a pavilion extending in a second direction from the girdle, opposite the first direction, the pavilion having eight main pavilion facets each of which extend from the girdle to a bottom of the pavilion, sixteen upper half facets, and sixteen lower half facets, wherein a respective pair of the sixteen upper half facets are positioned between adjacent facets of the eight main pavilion facets and the girdle, and a respective pair of the sixteen lower half facets are positioned between adjacent facets of the sixteen upper half facets and the girdle, wherein the eight main facets are at an angle of approximately 32-36° relative to a first plane parallel to a surface of the table, the eight star facets are at an angle of approximately 22-26° relative to the first plane, the sixteen top-half facets are at an angle of approximately 39-44° relative to the first plane, the eight main pavilion facets are each at an angle of approximately 40.6-41.4° relative to a second plane parallel to a face of the girdle, the sixteen upper half facets are each at an angle of approximately 41.4-42° relative to the second plane, and the sixteen lower half facets are each at an angle of approximately 42-42.9° relative to the second plane.
 2. The gemstone according to claim 1, wherein each of the eight star facets defines a respective side of the table.
 3. The gemstone according to claim 1, wherein a height of the crown is between 12.5 to 19.5% of a diameter of the gemstone.
 4. The gemstone according to claim 1, wherein a depth of the gemstone is between 59-62.9% of a diameter of the gemstone.
 5. The gemstone according to claim 1, wherein a depth of the pavilion is between 42.9 to 44.5% of a diameter of the gemstone.
 6. The gemstone according to claim 1, wherein a diameter of the table is between 53-60% of the width of the gemstone,
 7. The gemstone according to claim 1, wherein a thickness of the girdle is 1% to 7% of a diameter of the gemstone.
 8. The gemstone according to claim 1, wherein the bottom of the pavilion is a culet.
 9. The gemstone according to claim 8, wherein the culet has an area of 3% or less of the diameter of the gemstone.
 10. The gemstone according to claim 1, wherein the gemstone has an average 96% light performance characteristic.
 11. The gemstone according to claim 1, wherein: a height of the crown is between 12.5 to 19.5% of a diameter of the gemstone, a depth of the gemstone is between 59-62.9% of the diameter of the gemstone, a depth of the pavilion is between 42.9 to 44.5% of the diameter of the gemstone, and a diameter of the table is between 53-60% of the width of the gemstone. 